Hello to all,
I am planning to soon begin construction of my first Pizza oven (allthough i have participated in a quick and rough construction in a oven building workshop) which I hope to make a interesting object (see my CAD images) but I am worried that the aesthetic aspect of my design might compromise its basic functionality! I'm hoping that anybody with some experience with wood fired ovens could help, any advice would be much appreciated!

The images are only rough and dimensions are yet to be finalized, I have a reasonable amount of building experience and I am confident that I can build it (it will be difficult but I have a plan) and that it will be structurally sound. However I worry that: Firstly, the angled flue (see section drawing) will hinder ideal air currents and that the oven might smoke through the door or the fire simply won't burn properly? And secondly that the design concept forces the interior dome (ie. the oven) to be located in the volume of the 'sphere' at a impractical distance, that is, the front of the oven cavity will be approximately 700-800mm in from the exterior surface ,i.e. beyond reach by arm, so that cooking and the cleaning of the inside will only be able to be done with tools attached to rods, extended to be able to reach the interior space... do you think this would be too impractical?

It looks good. We actually had a member who built a spherical oven enclosure (unique oven enclosure): it was inside a channel marker buoy, and the steel shell formed the exterior of the enclosure. There's no problem with the angled chimney: a lot of Italian pizzaria ovens have the vent offset so it comes out the top of the dome. If you place your oven more to the rear of the enclosure you'll have more room for the entry/vent area.

My main concern is that if you build the outer enclosure of brick it may not be water resistant enough. You may have to do some sort of inner liner over the insulation, then have drip gaps in the brick below the oven floor. You'll also want some sort of drip ledge over your oven door.

A final thought is that the angled section of the flue may not be sufficient to prevent smoke leak on startup, but a chimney extension on top may not be the look you're going after.

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Hi Jack and welcome aboard,
Great to see yet another Aussie on deck ready to face an oven build.
Your project looks quite impressive and challenging to say the least but I feel achievable.
Put a few words about how you intend to construct it and as shown, I am sure that other members will chime in to offer advice on your thoughts/plans.

One way to make the oven easier to reach inside would be to keep the large outer ball and bring the oven further forward within it. There is no real need to have the oven in the center of the ball and you still should have room for the smoke vent over the top of the oven. The larger area at the back of the oven could just be fill or more insulation.

I'm sure you'll want to insure the ultimate performance of your oven. One thing in your design that strikes my concern is how you plan adequate insulation between the dome mass and chimney flue (given such a confined space). Without adequate insulation, the heat will migrate from the dome directly to the flue and decrease and otherwise interfere with the heat holding capabilies of your oven.

If you bake only pizza, that is not a big deal. If you want to bake bread and such, the impact would be greater.

You have a fabulous imagination and obvious creativity....Good luck and enjoy the process

Jack,
I just updated my Aussie list. You are now on the Melbourne list.
Just reading your plan of attack, one hell of a lot of bricks and cutting amongst other potential nightmares.
I see a problem getting your mortar joints in the lower hemispherical sphere accurate and even especially when hidden in the earth pattern. Maybe cut a heap of high density plastic strips 10mm wide and use them as spacers which after you remove the mound, pull them out and point the joint to suite your likes.
I have also been thinking of pre-casting 2 reinforced concrete semi spheres, one for the top and the other for the bottom of your build. You might even be able to include some reinforcing/retaining galv wires around the proposed mortar joints for the rows of bricks and cut/lay the bricks and then using a crane/loader/forklift place them into position. This would make the tasks of even brickwork and better shape much easier but sets up another challenge in positioning.
The bottom one would be easy once you overturned it, leaving a large circular hole left to allow your reinforcing steel to protrude, easy to pour your concrete and rubble fill.
The top one could locate over a raised locating concrete rim which can be done with your inner fill, but this would go on after your hearth, oven dome with insulation, and chimney. Putting just the precast semi sphere on would then be easy as your opening would be cut out and then brick your outer bricks.
Again, thinking outside the sphere highlights options which might make the task easier/quicker/better.
Good luck.

Dmon: when you say that you worry about the water resistance of the outer brick enclosure, is this because your thinking that the insulation may become saturated and not perform correctly? I was thinking that I would, after constructing the interior dome and covering it in insulation, I would put a thin layer of concrete reinforced with chicken wire which the outer brickwork would subsequently be laid on (see my section drawing), perhaps if you think that this is insufficient I could cover the concrete in water proofing membrane first, or just use a water-proofing agent in the mortar mix that brickwork will sit on?... Not sure what you mean by “drip gaps in the brick below the oven floor” could you elaborate?... I’m not too keen on the idea of building the chimney up, but if it turns out that it doesn’t draw the smoke properly I could always build it up after..

My only concern is that your brick sphere is going to soak up water like a sponge when it rains. If you make an inner waterproof layer, separated by a gap from your outer brick layer, and give some way for any moisture that accumulates a way to get out, then your oven may have a better chance of success. If you look around your neighborhood you won't see many homes with brick roofs. The porous brick structures are always capped with some sort of stone, shingle, or flashing to deflect moisture away from the brick structure. In those rare instances where bricks are exposed horizontally, like front steps, it's not unusual to see them crumble away in a few years from freeze/thaw cycles. Also, in that particular instance, the steps are usually filled with some kind of rubble which it's not important to keep dry.

I'm not proposing a solution, just suggesting you give the water issue some thought.

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